Chapter Text
Grinning like he’s just won the lottery, Stiles adds a second finger.
Derek moans through the teeth clenched tight around his bottom lip.
Stiles takes his hand completely off of Derek’s dick and sits back in a crouch between his legs. Derek lets go of his lip and groans, spreading his legs wider around Stiles’ hips. Stiles scissors his fingers apart, stretching. Less distracted now, Stiles can feel how hot Derek is inside, how tight. He chokes down a moan of his own.
He presses a third finger in alongside the first two.
Derek hisses and then bucks against his hand. His hips make tiny little jerking motions against him, and Stiles watches in hazy lust filled fascination.
“Stiles.” Derek’s cheeks are red and his face is loose and relaxed. Stiles swallows thickly.
“Yeah?”
Derek just nods.
Pulling his fingers out of Derek’s body is the second hottest thing Stiles has ever experienced. He braces his hands under Derek’s hips and pulls him up a bit. There’s an awkward moment where Stiles frantically tries to figure out how this angle is going to work, but then Derek is shoving a pillow under his hips and pulling him forward. Stiles sits up on his knees, watching as he lines himself up.
And then he’s pressing in. It’s hotter and tighter and better than anything he imagined, and he’s trying to work his way in slowly, but it’s so hard. He’s so hard, and Derek is opening up so smoothly for him, and he’s just sinking in so beautifully. And then Derek is pulling him forward again, and his hips are flush against Derek’s ass.
“Oh my god.”
Derek tightens his legs around Stiles’ waist, and Stiles isn’t entirely sure when he put them there in the first place.
“Stiles. Move.”
So he does. Stiles tightens his hold on Derek’s hips and pulls back as much as he can without coming out completely, and then he presses back in slowly. He has to pause once he’s all the way back in, overwhelmed by the sudden realization that he’s here and this is happening and he’s having sex. With Derek.
He’s inside Derek.
He darts his eyes to Derek’s face, expecting his eyes to be closed, his head back, relaxed, hopefully enjoying himself. Instead their eyes meet and lock onto one another, mouths open and panting, faces flushed. Derek’s nostrils flare, and Stiles knows he can smell this, even more than he can. He can smell their sex and arousal combined like this. The thought is hotter than he anticipated.
His hips jerk forward and they moan simultaneously. Stiles tears his eyes away from Derek’s and focuses on where they’re joined. He breathes deeply and starts up a steady rhythm of thrusting, changing the angle every so often to see how Derek reacts. He pulls Derek’s hips just a little closer and thrusts in hard, and suddenly he feels Derek clenching down on him as he positively howls. Stiles’ vision goes blurry at the edges.
He does it again. And again. His hips stutter against Derek’s, driving in deep, and at just the right angle. He’s sweating and panting, heart racing as his body takes over. Derek’s comforter is a shredded mess underneath his hands, and he’s making noises Stiles’ has only ever heard in porn. And that gives Stiles an idea.
Taking one hand off Derek’s hips, he reaches out and grabs hold of his cock. Its seems even bigger now, leaking almost steadily against his stomach as it bounces with the force of his thrusts. Derek’s hips start moving with him as he strokes up his shaft, thumb toying with the foreskin. He can feel his own orgasm building fast, hips faltering in their pattern, body singing with the pleasure of it.
Suddenly he’s on his back and Derek is sinking back down onto his cock, legs bouncing under him and palms flat against the bed on either side of Stiles’ abdomen. Stiles manages to wrap his hand back around Derek loosely, letting him fuck up into it as he fucks himself back and forth on Stiles’ cock.
Stiles pulls his knees up and presses forward as Derek comes back down. He tightens his grip a little on Derek’s dick and thrusts once as hard as he can, and then he’s coming. Stiles’ insides feel like they’ve been liquefied and mixed with lighter fluid. His body is shaking and every nerve he has is on fire, and, distantly, he’s aware of Derek still rocking back onto him.
He’s half conscious with pleasure, but he knows the exact moment Derek shakes apart on top of him. He’s suddenly squeezing tighter around him and pulsing in his hand, legs stilling as his whole body tenses. And the sound. Derek comes with a low, deep moan that sounds like it was ripped straight from his soul, and Stiles can’t help but fight his eyes to stay open and watch.
He starts to let go of Derek’s cock, figuring he’s probably just as over sensitive as he is, but the pitiful whine Derek looks surprised to be making stops him.
Stiles blinks up at Derek. Derek, who is hunched over Stiles protectively, still pressed flush against his hips, and who has left what looks like at least twice the normal amount of come on Stiles’ stomach.
“Been a while?” Stiles curses his pathetic sense of humor when Derek stays quiet. He looks up at his face and pales.
Derek looks kind of horrified. His eyes are back to normal, all green hazel, but the color has drained from his face. Stiles tries to pull his hand away again, but Derek slams his eyes shut and makes that same high pitched whine. Derek’s hips jerk against him, and he can’t help but hiss just a little at the overstimulation.
“Sorry. I, uh—“ Derek shifts again and appears to try to pull away from him. He can’t quite bring himself to do it though, and the shift in position lets Stiles get a good look at just what’s going on.
“Oh.” Stiles’ hand is still wrapped around the base of Derek’s cock. Which. Um. Yeah. It’s definitely at least two inches wider at the bottom than it was before.
Stiles squeezes a bit experimentally. Derek sighs and relaxes.
“So. I’m guessing, judging by the mix of horror and intrigue on your face, that this doesn’t happen every time?” Stiles flexes his fingers again, and Derek grimaces.
“It generally only happens when I’m partially shifted. And it doesn’t usually happen without me being aware of it.” His tone is a mix of apologetic and something that sounds suspiciously like shame.
“Dude. It’s okay. I just wasn't expecting it. Are you gonna whine like that if I try to take my hand away again, or was that just surprise?”
The expression he makes answers for him, and Stiles can't help but let out a breathy giggle.
"So I've got permission to play with your dick for a while?"
Derek groans and leans forward, resting his head against Stiles' chest.